A LADAR transmitting and receiving system and method is disclosed in U.S. Pat. No. 8,081,301 (hereinafter '301 patent), hereby incorporated by reference. The '301 patent discloses a compact LADAR transmitting and receiving apparatus including a pulse laser generating pulses of light; a transmitter collimating and directing the pulses of light toward a target; a receiver collecting reflected pulses of light, the reflected pulses of light having been reflected from the target, the receiver comprising a tapered fiber bundle; a sensor operatively connected to the tapered fiber bundle, where the sensor comprises a photosensitive region and outputs a photocurrent; an amplifier amplifying the photocurrent; and a power divider splitting the amplified photocurrent between a high gain channel and a low gain channel; a RF interface accepting the high gain channel, the low gain channel, and an undelayed sample of a pulse of light generated from the pulse laser as input; a processing unit accepting output from the RF interface; and a display unit displaying output from the processing unit. The display unit formats the received data to form a three dimensional imager representing the position and range to objects in the surrounding area. This 3-D display is presented to the user in either a false color or stereoscopic format to represent the position and range information and updated periodically each time the ladar completes a scan. This micro-electro-mechanical system (MEMS) based Wide-FOV ladar uses a non-imaging optic based receiver designed to achieve the wide FOV. For certain applications requiring increased performance, such as imaging targets at a longer range, a receiver with higher optical gain would be desirable. However, since the field of view of the system disclosed in the '301 patent is very large, receivers using a classical optics design do not achieve the desired optical gain.
The embodiment described in the '301 patent was developed to meet specific size, weight, power and cost constraints for a small robot application. Other applications, such as helicopter aided landing, have similar size, weight, power and cost constraints but require much higher ranging performance to measure targets at further distances. The increased range requirement can be met by increasing the laser power; which are technically viable but a significant power increase is not feasible if the design is to stay within the size, weight, power and cost constraints.